NetNewsWire/Shared/Commands/DeleteCommand.swift

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//
// DeleteFromSidebarCommand.swift
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// NetNewsWire
//
// Created by Brent Simmons on 11/4/17.
// Copyright © 2017 Ranchero Software. All rights reserved.
//
import Foundation
import RSCore
import RSTree
import Account
import Articles
final class DeleteCommand: UndoableCommand {
let treeController: TreeController
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let undoManager: UndoManager
let undoActionName: String
var redoActionName: String {
return undoActionName
}
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private let itemSpecifiers: [SidebarItemSpecifier]
init?(nodesToDelete: [Node], treeController: TreeController, undoManager: UndoManager) {
guard DeleteCommand.canDelete(nodesToDelete) else {
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return nil
}
guard let actionName = DeleteActionName.name(for: nodesToDelete) else {
return nil
}
self.treeController = treeController
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self.undoActionName = actionName
self.undoManager = undoManager
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let itemSpecifiers = nodesToDelete.compactMap{ SidebarItemSpecifier(node: $0) }
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guard !itemSpecifiers.isEmpty else {
return nil
}
self.itemSpecifiers = itemSpecifiers
}
func perform() {
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BatchUpdate.shared.perform {
itemSpecifiers.forEach { $0.delete() }
treeController.rebuild()
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}
registerUndo()
}
func undo() {
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BatchUpdate.shared.perform {
itemSpecifiers.forEach { $0.restore() }
treeController.rebuild()
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}
registerRedo()
}
static func canDelete(_ nodes: [Node]) -> Bool {
// Return true if all nodes are feeds and folders.
// Any other type: return false.
if nodes.isEmpty {
return false
}
for node in nodes {
if let _ = node.representedObject as? Feed {
continue
}
if let _ = node.representedObject as? Folder {
continue
}
return false
}
return true
}
}
// Remember as much as we can now about the items being deleted,
// so they can be restored to the correct place.
private struct SidebarItemSpecifier {
private weak var account: Account?
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private let parentFolder: Folder?
private let folder: Folder?
private let feed: Feed?
private let path: ContainerPath
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private var container: Container? {
if let parentFolder = parentFolder {
return parentFolder
}
if let account = account {
return account
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}
return nil
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}
init?(node: Node) {
var account: Account?
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self.parentFolder = node.parentFolder()
if let feed = node.representedObject as? Feed {
self.feed = feed
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self.folder = nil
account = feed.account
}
else if let folder = node.representedObject as? Folder {
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self.feed = nil
self.folder = folder
account = folder.account
}
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else {
return nil
}
if account == nil {
return nil
}
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self.account = account!
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self.path = ContainerPath(account: account!, folders: node.containingFolders())
}
func delete() {
guard let container = container else {
return
}
if let feed = feed {
container.deleteFeed(feed)
}
else if let folder = folder {
container.deleteFolder(folder)
}
}
func restore() {
if let _ = feed {
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restoreFeed()
}
else if let _ = folder {
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restoreFolder()
}
}
private func restoreFeed() {
guard let account = account, let feed = feed else {
return
}
account.addFeed(feed, to: resolvedFolder())
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}
private func restoreFolder() {
guard let account = account, let folder = folder else {
return
}
account.addFolder(folder, to: nil)
}
private func resolvedFolder() -> Folder? {
return path.resolveContainer() as? Folder
}
}
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private extension Node {
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func parentFolder() -> Folder? {
guard let parentNode = self.parent else {
return nil
}
if parentNode.isRoot {
return nil
}
if let folder = parentNode.representedObject as? Folder {
return folder
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}
return nil
}
func containingFolders() -> [Folder] {
var nomad = self.parent
var folders = [Folder]()
while nomad != nil {
if let folder = nomad!.representedObject as? Folder {
folders += [folder]
}
else {
break
}
nomad = nomad!.parent
}
return folders.reversed()
}
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}
private struct DeleteActionName {
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private static let deleteFeed = NSLocalizedString("Delete Feed", comment: "command")
private static let deleteFeeds = NSLocalizedString("Delete Feeds", comment: "command")
private static let deleteFolder = NSLocalizedString("Delete Folder", comment: "command")
private static let deleteFolders = NSLocalizedString("Delete Folders", comment: "command")
private static let deleteFeedsAndFolders = NSLocalizedString("Delete Feeds and Folders", comment: "command")
static func name(for nodes: [Node]) -> String? {
var numberOfFeeds = 0
var numberOfFolders = 0
for node in nodes {
if let _ = node.representedObject as? Feed {
numberOfFeeds += 1
}
else if let _ = node.representedObject as? Folder {
numberOfFolders += 1
}
else {
return nil // Delete only Feeds and Folders.
}
}
if numberOfFolders < 1 {
return numberOfFeeds == 1 ? deleteFeed : deleteFeeds
}
if numberOfFeeds < 1 {
return numberOfFolders == 1 ? deleteFolder : deleteFolders
}
return deleteFeedsAndFolders
}
}